JP6845484B2 - Imaging optical system, lens unit and imaging device - Google Patents

Description

The present invention relates to an image pickup optical system, a lens unit, and an image pickup device. More specifically, the present invention relates to an image pickup optical system and a lens unit suitable for applications such as an in-vehicle camera using an image pickup element, a camera for a mobile terminal, and a surveillance camera, and an image pickup. It relates to an image pickup apparatus provided with an optical system.

Image sensors such as CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) have been extremely miniaturized and have a high pixel count in recent years. At the same time, the main body of the image pickup device equipped with these image pickup elements is also becoming smaller, and the image pickup lens mounted on the image sensor is also required to be smaller and lighter in addition to good optical performance. On the other hand, in-vehicle cameras and surveillance cameras, for example, have a bright optical system with an F value of 2.0, and can be used in a wide temperature range from the outside air in cold regions to the inside of cars in summer in tropical regions while having high weather resistance. There is a demand for inexpensive and wide-angle lenses.

An optical system using a plastic lens can be mentioned in order to have an inexpensive configuration (see, for example, Patent Documents 1 to 4). When a plastic lens is used, the cost and weight can be reduced as compared with the case where a glass lens is used. However, the refractive index of the glass material is almost constant even when the temperature changes, but the change of the refractive index of the plastic material when the temperature changes is larger than that of the glass material regardless of the type. Therefore, when a wide-angle lens that uses a lot of plastic lenses is used, there is a drawback that the focus position changes relatively greatly depending on the environmental temperature and the resolution fluctuates.

In Patent Document 1, cost reduction and weight reduction can be achieved by using plastic for all lenses, but since the power setting of the plastic lens is not appropriate, the amount of focus movement when the temperature changes becomes large. ing. Moreover, not only the center is out of focus, but also the movement of the image plane around the center is large, which causes a problem in actual use.

In Patent Document 2, although a plastic lens is frequently used, good optical performance cannot be ensured, and the optical performance is not suitable for an image sensor whose miniaturization and high pixel count have been progressing in recent years.

In Patent Document 3, it is attempted to reduce performance deterioration and focus movement when the temperature changes by using glass for the lens around the diaphragm having a thick luminous flux. In a harsh environment, the amount of focus movement is still large and the performance is greatly deteriorated, which causes a problem in actual use.

In Patent Document 4, not only a plastic lens but also a glass lens is used to achieve cost reduction and weight reduction. However, since the plastic lens is used around the diaphragm having a thick luminous flux, the amount of focus movement when the temperature changes. Is becoming larger, causing problems in actual use.

JP 2015-034922 Japanese Unexamined Patent Publication No. 2014-209227 Japanese Unexamined Patent Publication No. 2014-089349 Japanese Unexamined Patent Publication No. 2006-284620

The present invention has been made in view of such a problem, and an object of the present invention is to provide an image pickup optical system having a wide angle of view, inexpensive, and capable of ensuring good optical performance, and having high weather resistance.

Another object of the present invention is to provide a lens unit and an imaging device provided with the above-mentioned imaging optical system.

In order to achieve at least one of the above-mentioned objects, the first imaging optical system reflecting one aspect of the present invention has the first lens group, the aperture, and the second lens group in order from the object side. The first lens group includes a first lens having a negative refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power in this order from the object side. And a fourth lens having a positive refractive power, three of the four lenses in the first lens group are made of plastic or resin, and the second lens group is made of plastic. Alternatively, it has at least one lens formed of resin and having a positive refractive force and one lens formed of plastic or resin and having a negative refractive force, and the object side surface of the second lens is the object side in the vicinity of the optical axis. Although it is concave, it has a shape located on the image side of the surface apex position on the optical axis at the effective diameter position, and satisfies the following conditional expression.
−0.32 ≦ F × Σ (1 / fplk) ≦ 0.32… (1)
However, the value F is the focal length of the entire system, and the value fplk is the focal length of the kth (k is a natural number) plastic lens from the object side.

In order to achieve at least one of the above-mentioned objects, the second imaging optical system reflecting one aspect of the present invention has the first lens group, the aperture, and the second lens group in order from the object side. In the imaging optical system provided, the first lens group includes a first lens having a negative refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power in this order from the object side. And a fourth lens having a positive refractive power, three of the four lenses in the first lens group are made of plastic or resin, and the second lens group is made of plastic. Alternatively, it has at least one lens made of resin and having a positive refractive power and one lens made of plastic or resin having a negative refractive power, and the lens on the most object side of the second lens group is a positive lens. The glass lens, which is composed of a glass lens having a refractive force and is located closest to the object in the second lens group, satisfies the following conditional expression.
nd5 ≧ 1.7… (10)
νd5 ≧ 40… (11)
However, the value nd5 is the refractive index of the glass lens on the most object side of the second lens group, and the value νd5 is the Abbe number of the glass lens on the most object side of the second lens group.

Further, the lens unit reflecting one aspect of the present invention includes the above-mentioned imaging optical system and a lens barrel that holds the imaging optical system.

Further, the image pickup apparatus reflecting one aspect of the present invention includes the above-mentioned image pickup optical system and an image pickup element for detecting an image obtained from the image pickup optical system.

It is a figure explaining the lens unit and the image pickup apparatus which include the image pickup optical system of one Embodiment of this invention. FIG. 2A is a cross-sectional view showing an imaging optical system and the like according to the first embodiment, and FIGS. 2B and 2C are aberration diagrams. FIG. 3A is a cross-sectional view showing the imaging optical system and the like of the second embodiment, and FIGS. 3B and 3C are aberration diagrams. 4A is a cross-sectional view showing the imaging optical system and the like of the third embodiment, and FIGS. 4B and 4C are aberration diagrams. 5A is a cross-sectional view showing the imaging optical system and the like of Example 4, and FIGS. 5B and 5C are aberration diagrams. FIG. 6A is a cross-sectional view showing the imaging optical system of Example 5, and FIGS. 6B and 6C are aberration diagrams. FIG. 7A is a cross-sectional view showing the imaging optical system of Example 6, and FIGS. 7B and 7C are aberration diagrams. 8A is a cross-sectional view showing the imaging optical system and the like of Example 7, and FIGS. 8B and 8C are aberration diagrams. 9A is a cross-sectional view showing the imaging optical system of Example 8, and FIGS. 9B and 9C are aberration diagrams. 10A is a cross-sectional view showing an imaging optical system and the like of Example 9, and FIGS. 10B and 10C are aberration diagrams. 11A is a cross-sectional view showing the imaging optical system and the like of Example 10, and FIGS. 11B and 11C are aberration diagrams.

FIG. 1 is a cross-sectional view showing an image pickup apparatus 100 according to an embodiment of the present invention. The image pickup device 100 includes a camera module 30 for forming an image signal, and a processing unit 60 that exerts a function as the image pickup device 100 by operating the camera module 30.

The camera module 30 includes a lens unit 40 having a built-in image pickup optical system 10 and a sensor unit 50 that converts a subject image formed by the image pickup optical system 10 into an image signal.

The lens unit 40 includes an imaging optical system 10 which is a wide-angle optical system, and a lens barrel 41 incorporating the imaging optical system 10. The imaging optical system 10 is composed of the first to seventh lenses L1 to L7. The lens barrel 41 is made of resin, metal, a mixture of resin and glass fiber, or the like, and houses and holds a lens or the like inside. When the lens barrel 41 is formed of a mixture of metal or resin and glass fiber, it is less likely to expand thermally than resin, and the imaging optical system 10 can be stably fixed. The lens barrel 41 has an opening OP for incident light from the object side.

The total angle of view of the imaging optical system 10 is 180 ° or more. The first to seventh lenses L1 to L7 constituting the imaging optical system 10 are directly or indirectly held on the inner surface side of the lens barrel 41 at their flanges or outer peripheral portions, and are directly or indirectly held in the optical axis AX direction and light. Positioning is done in the direction perpendicular to the axis AX.

The sensor unit 50 includes an image pickup element (solid-state image pickup element) 51 that photoelectrically converts a subject image formed by the image pickup optical system (wide-angle optical system) 10, and a substrate 52 that supports the image pickup element 51. The image sensor 51 is, for example, a CMOS type image sensor. The substrate 52 includes wiring for operating the image pickup device 51, peripheral circuits, and the like. The image sensor 51 and the like are positioned and fixed with respect to the optical axis AX by a holder member (not shown). This holder member is fixed in a positioned state so as to fit into the lens barrel 41 of the lens unit 40.

The image sensor 51 has a photoelectric conversion unit 51a provided with an image pickup surface I, and a signal processing circuit (not shown) is formed around the photoelectric conversion unit 51a. Pixels, that is, photoelectric conversion elements are two-dimensionally arranged in the photoelectric conversion unit 51a. The image sensor 51 is not limited to the above-mentioned CMOS type image sensor, and may incorporate another image sensor such as a CCD.

A filter F or the like can be arranged between the lenses constituting the lens unit 40 or between the lens unit 40 and the sensor unit 50. In the example of FIG. 1, the filter F is arranged between the seventh lens L7 of the image pickup optical system 10 and the image pickup element 51. The filter F is a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of the image sensor 51, and the like. The filter F can be arranged as a separate filter member, but it is not arranged as a separate body, and the function can be imparted to any lens surface constituting the imaging optical system 10. For example, in the case of an infrared cut filter, an infrared cut coat may be applied on the surface (optical surface) of one or a plurality of lenses.

The processing unit 60 includes an element driving unit 61, an input unit 62, a storage unit 63, a display unit 64, and a control unit 68. The element drive unit 61 outputs a YUV or other digital pixel signal to an external circuit (specifically, a circuit attached to the image sensor 51 or the like), or drives a voltage or clock signal from the control unit 68 to drive the image sensor 51. The image sensor 51 is operated by receiving the supply of the image sensor 51. The input unit 62 is a part that receives a user's operation or a command from an external device, and the storage unit 63 is a part that stores information necessary for the operation of the image pickup device 100, image data acquired by the camera module 30, and the like. Yes, the display unit 64 is a portion that displays information to be presented to the user, a captured image, and the like. The control unit 68 comprehensively controls the operations of the element drive unit 61, the input unit 62, the storage unit 63, and the like, and can perform various image processing on the image data obtained by, for example, the camera module 30. ..

Although detailed description is omitted, the specific function of the processing unit 60 is appropriately adjusted according to the application of the device in which the image pickup apparatus 100 is incorporated. The image pickup device 100 can be mounted on devices for various purposes such as an in-vehicle camera and a surveillance camera.

Hereinafter, the imaging optical system (wide-angle optical system) 10 and the like of the first embodiment will be described with reference to FIG. The imaging optical system 10 illustrated in FIG. 1 has substantially the same configuration as the imaging optical system 10A of the first embodiment described later.

The illustrated imaging optical system (wide-angle optical system) 10 includes a first lens group Gr1, an aperture diaphragm ST, and a second lens group Gr2 in order from the object side. The first lens group Gr1 includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and positive lenses in this order from the object side. It becomes substantially from the fourth lens L4 having a refractive power. Of the four lenses of the first lens group Gr1, three lenses are made of plastic or resin. Further, the first lens L1 is a glass lens. In the optical system used for in-vehicle cameras and surveillance cameras, the lens located closest to the object is exposed to the outside world, so that it is easily scratched. In order to avoid such scratches, it is desirable to use a lens that is not easily scratched, such as a glass lens, as the lens located closest to the object. By using the first lens L1 located closest to the object as a glass lens, scratches and the like can be prevented, and it is easy to maintain good optical performance for a long period of time.

Further, the side surface of the object of the second lens L2 has a shape that is concave on the object side in the vicinity of the optical axis AX but is located on the image side from the surface apex position on the optical axis AX at the effective diameter position. With wide-angle lenses such as in-vehicle and fisheye lenses, the peripheral angle of view is large, so the first and second negative lenses are meniscus with a convex surface facing the object side in order to minimize the aberration that occurs at the peripheral image height. It tends to be in the shape of a lens. By making the side surface of the object of the second lens L2 concave, the angle of incidence of the axial light beam on the side surface of the object can be reduced, so that spherical aberration generated by the axial light beam can be suppressed. Further, by forming the side surface of the object of the second lens L2 to be located on the image side from the surface apex position at the effective diameter position, the angle of incidence of the light ray on the lens surface is particularly high in the peripheral image height with respect to the light ray from the off-axis. Therefore, the coma aberration generated by the light beam from the off-axis can be reduced.

The second lens group Gr2 includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power in order from the object side. A lens having another refractive power may be added to the second lens group Gr2, but it is more preferable that the second lens group Gr2 is composed of only a positive lens, a negative lens, and a positive lens in order from the object side. The positive / negative / positive configuration in the second lens group Gr2 is a so-called triplet configuration. Since various aberrations can be satisfactorily corrected by this triplet configuration, good optical performance can be ensured. That is, the second lens group Gr2 has at least one lens formed of plastic or resin and having a positive refractive power and one lens formed of plastic or resin and having a negative refractive power. Further, the lens located closest to the object side of the second lens group Gr2, that is, the fifth lens L5 is a glass lens having a positive refractive power. Compared to plastic lenses, glass lenses have a smaller change in refractive index per unit temperature. In general, thick light rays pass near the aperture stop ST, so if a plastic lens is used near the aperture stop ST, focus movement and aberration fluctuations will increase when a temperature change occurs. Not preferable. By using the lens located closest to the object in the second lens group Gr2, that is, the fifth lens L5 as a glass lens, that is, by using the fifth lens L5 immediately after the aperture stop ST through which a thick light ray passes as a glass lens. , It is possible to prevent remarkable focus movement and performance deterioration.

The imaging optical system (wide-angle optical system) 10 satisfies the following conditional expression (1).
−0.32 ≦ F × Σ (1 / fplk) ≦ 0.32… (1)
However, the value F is the focal length of the entire system, and the value fplk is the focal length of the kth (k is a natural number) plastic lens from the object side.

The conditional expression (1) is an expression obtained by summing the powers of the plastic lenses in the imaging optical system and multiplying them by the focal length. When using a plastic lens, if the power of the plastic lens is not set appropriately, the amount of focus movement and the amount of change in aberration when the temperature changes will be large, and the imaging position will change significantly and the performance will be large. It deteriorates. In order to suppress focus movement and aberration fluctuation due to temperature change, it is preferable that the combined powers of the positive plastic lens and the negative plastic lens cancel each other out, and it is necessary to make the difference small. By satisfying the conditional expression (1), it is possible to set an appropriate power of the plastic lens of the imaging optical system 10, and it is possible to reduce the focus movement when the temperature changes. Specifically, by setting the value F × Σ (1 / fplk) of the conditional expression (1) to the upper limit or less, the positive combined power does not become too strong, and the back focus occurs when the temperature changes to the low temperature side. It is possible to suppress the decrease in the back focus and the increase in the back focus when the temperature changes to the high temperature side. On the other hand, by setting it to the lower limit value or more of the conditional expression (1), the negative combined power does not become too strong, the increase in back focus can be suppressed when the temperature changes to the low temperature side, and the temperature is on the high temperature side. When it changes to, the decrease in back focus can be suppressed. The closer the value of the conditional expression (1) is to 0, the more desirable it is, but it does not necessarily have to be 0 due to the allowable depth of the lens, etc., and if the range of the conditional expression (1) is satisfied, deterioration of performance is suppressed even when the temperature changes. be able to. Further, by setting the condition expression (1) to be within the range of the conditional expression (1) even if the value is not 0, it becomes easier to correct the aberration as compared with the case where the value of the conditional expression (1) is set to 0. , Performance at room temperature can also be ensured. By satisfying the range of the conditional expression (1) in this way, it is possible to achieve both the performance at the time of temperature change and the performance at room temperature.

It is more desirable that the conditional expression (1) is within the range of the conditional expression (14).
−0.32 ≦ F × Σ (1 / fplk) ≦ −0.10… (14)

In this embodiment, there are two positive plastic lenses in the vicinity of the aperture stop ST. Since a thick light beam passes through a lens located near the aperture stop ST, the imaging optical system 10 is easily affected by the power of this lens, and the contribution to focus movement when the temperature changes is large. When the temperature decreases, the refractive power of the plastic lens increases. As described above, the lens near the aperture stop ST is easily affected by the temperature change, and the back focus is reduced by increasing the power of the positive lens. As shown in conditional expression (14), the power of the negative lens is set so as to appropriately exceed the combined power of the positive lens including the two positive plastic lenses that exist near the aperture stop ST and are easily affected by the temperature. If this is done, it becomes easy to cancel the focus movement due to the change in the power of the positive lens near the aperture stop ST.

Further, in the imaging optical system 10, the two positive lenses and the two negative lenses in the first lens group Gr1 further satisfy the following conditional expression (2), respectively.
−0.47 ≦ f1n / f1p ≦ 0.00… (2)
However, the value f1n is the combined focal length of the first lens L1 and the second lens L2, and the value f1p is the combined focal length of the third lens L3 and the fourth lens L4.

Conditional expression (2) is the ratio of the combined focal length of the negative lens of the first lens group Gr1 to the combined focal length of the positive lens. The imaging optical system 10 of the present embodiment is a wide-angle lens particularly used for an in-vehicle camera and a surveillance camera. In the case of a wide-angle lens with a wide angle of view, a retrofocus type power arrangement composed of negative and positive powers is often adopted from the object side. In this case, by placing a negative power on the object side, the position of the entrance pupil can be placed closer to the object side, so that a wide angle of view can be secured while reducing the diameter of the front lens. By setting the value f1n / f1p of the conditional expression (2) to the upper limit or less, the negative power of the first lens group Gr1 does not become too strong, and the curvature of field and distortion of the peripheral image height that are likely to occur especially with a wide-angle lens. Aberration can be suppressed. In addition, since aberration fluctuations due to manufacturing errors can be suppressed, mass productivity can be ensured. On the other hand, by setting the value to the lower limit of the conditional expression (2) or more, the negative power does not become too weak, the position of the entrance pupil does not move excessively to the image side, and the front lens diameter is reduced even though the angle is wide. be able to.

Further, in the imaging optical system 10, the three plastic lenses of the first lens group Gr1 further satisfy the following conditional expression (3).
−0.85 ≦ F1 × Σ (1 / f1plk) ≦ 0.85… (3)
However, the value F1 is the composite focal length of the first lens group Gr1, and the value f1plk is the focal length of the kth plastic lens from the object side in the first lens group Gr1.

The conditional equation (3) is an equation obtained by summing the powers of the plastic lenses in the first lens group Gr1 and multiplying the combined focal length of the first lens group Gr1. When a plastic lens is used, the amount of focus movement and aberration fluctuation when a temperature change occurs become large. This is because the plastic lens has a larger change in the refractive index per unit temperature than the glass lens. It is necessary to set the power in the first lens group Gr1 within an appropriate range in order to suppress the amount of focus movement and the fluctuation of aberration when a temperature change occurs. By setting the value F1 × Σ (1 / f1plk) of the conditional expression (3) to the upper limit or less, the positive combined power in the first lens group Gr1 does not become too strong, and when the temperature changes to the low temperature side. The decrease in back focus can be suppressed, and the increase in back focus can be suppressed when the temperature changes to the high temperature side. In addition, it is possible to prevent deterioration of spherical aberration and coma caused by the positive combined power becoming too strong, and to secure good optical performance. On the other hand, by setting the value to the lower limit of the conditional expression (3) or more, the negative combined power in the first lens group Gr1 does not become too strong, and the increase in back focus can be suppressed when the temperature changes to the low temperature side. It is possible to prevent deterioration of performance and suppress a decrease in back focus when the temperature changes to the high temperature side. Further, it is possible to prevent the occurrence of curvature of field and distortion caused by the negative combined power becoming too strong, and it is possible to obtain good optical performance.

Further, in the imaging optical system 10, the two or more plastic lenses of the second lens group Gr2 further satisfy the following conditional expression (4).
−0.85 ≦ F2 × Σ (1 / f2plk) ≦ 0.85… (4)
However, the value F2 is the composite focal length of the second lens group Gr2, and the value f2plk is the focal length of the kth plastic lens from the object side in the second lens group Gr2.

The conditional equation (4) is an equation obtained by summing the powers of the plastic lenses in the second lens group Gr2 and multiplying the combined focal length of the second lens group Gr2. In the second lens group Gr2 as well, when a plastic lens is used as in the first lens group Gr1, it is necessary to prevent focus movement and performance deterioration due to temperature changes. By setting the value F2 × Σ (1 / f2plk) of the conditional expression (4) to the upper limit or less, the positive combined power in the second lens group Gr2 does not become too strong, and when the temperature changes to the low temperature side. The decrease in back focus can be suppressed, and the increase in back focus can be suppressed when the temperature changes to the high temperature side. In addition, it is possible to prevent deterioration of spherical aberration and coma caused by the positive combined power becoming too strong, and to secure good optical performance. On the other hand, by setting the value to the lower limit of the conditional expression (4) or more, the negative combined power in the second lens group Gr2 does not become too strong, and the increase in back focus is suppressed and the performance is suppressed when the temperature changes to the low temperature side. It is possible to prevent the deterioration of the back focus and suppress the decrease of the back focus when the temperature changes to the high temperature side.

Further, in the imaging optical system 10, the third lens L3 further satisfies the following conditional expression (5).
5.0 ≦ f3 / F ≦ 14.5… (5)
However, the value f3 is the focal length of the third lens L3.

By setting the value f3 / F of the conditional expression (5) to the upper limit value or less, the focal length of the third lens L3 does not become too long, and it is possible to prevent the imaging optical system 10 from becoming large. On the other hand, by setting the value to the lower limit of the conditional expression (5) or more, the focal length of the third lens L3 does not become too short, spherical aberration, coma, etc. can be corrected, and good optical performance can be ensured. Can be done. Further, since the aberration fluctuation due to the manufacturing error can be reduced, mass productivity can be ensured.

Further, in the imaging optical system 10, the fourth lens L4 further satisfies the following conditional expression (6).
7.0 ≤ f4 / F ≤ 15.1 ... (6)
However, the value f4 is the focal length of the fourth lens L4.

By setting the value f4 / F of the conditional expression (6) to the upper limit value or less, the focal length of the fourth lens L4 does not become too long, and it is possible to prevent the imaging optical system 10 from becoming large. On the other hand, by setting the value to the lower limit of the conditional expression (6) or more, the focal length of the fourth lens L4 does not become too short, spherical aberration, coma, etc. can be corrected, and good optical performance can be ensured. Can be done. Further, since the aberration fluctuation due to the manufacturing error can be reduced, mass productivity can be ensured.

Further, the imaging optical system 10 further satisfies the following conditional expression (7).
0.3 ≤ F1 / F2 ≤ 5.3 ... (7)
However, the value F1 is the composite focal length of the first lens group Gr1, and the value F2 is the composite focal length of the second lens group Gr2.

The conditional expression (7) is the ratio of the focal lengths of the first lens group Gr1 and the second lens group Gr2. By setting the value F1 / F2 of the conditional expression (7) to the upper limit value or less, the focal length of the first lens group Gr1 does not become too long with respect to the second lens group Gr2, and the size of the imaging optical system 10 is prevented from becoming large. At the same time, good optical performance can be ensured. On the other hand, when the value is equal to or greater than the lower limit of the conditional expression (7), the focal length of the first lens group Gr1 is not too short with respect to the second lens group Gr2, which is particularly remarkable in an optical system having a large angle of view. It is possible to prevent the curvature of field and the distortion of the image height from becoming large, and it is possible to secure good optical performance while reducing the size. Further, the power of the first lens group Gr1 does not become too strong, aberration fluctuations due to manufacturing errors can be suppressed, and mass productivity can be ensured.

Further, in the imaging optical system 10, the first lens L1 further satisfies the following conditional expressions (8) and (9).
nd1 ≧ 1.7… (8)
νd1 ≧ 40… (9)
However, the value nd1 is the refractive index of the first lens L1, and the value νd1 is the Abbe number of the first lens L1.

The lens on the most object side of the first lens group Gr1, that is, the first lens L1, has a large angle of view of the peripheral image height, so that light rays pass through a high position. Therefore, the influence of the first lens L1 on the peripheral performance is large, and the curvature of field, the distortion, and the chromatic aberration of magnification are particularly large. In order to reduce the occurrence of curvature of field and distortion, it is necessary to use a glass material with a high refractive index and reduce the radius of curvature of the lens surface. Resulting in. In order to correct chromatic aberration of magnification, it is necessary to use a glass material with a small dispersion, but since a glass material with a small dispersion generally has a low refractive index, the radius of curvature of the lens surface must be reduced in order to obtain power. However, curvature of field and distortion become worse. By using a glass material that satisfies the conditional equations (8) and (9), it is possible to reduce the chromatic aberration of magnification while suppressing the occurrence of curvature of field and distortion, ensuring good optical performance. can do.

Further, in the imaging optical system 10, the glass lens located closest to the object side of the second lens group Gr2 further satisfies the following conditional expressions (10) and (11).
nd5 ≧ 1.7… (10)
νd5 ≧ 40… (11)
However, the value nd5 is the refractive index of the glass lens on the most object side of the second lens group Gr2, and the value νd5 is the Abbe number of the glass lens on the most object side of the second lens group Gr2.

Since the lens located closest to the object side of the second lens group Gr2, that is, the fifth lens L5, is located immediately after the aperture stop ST, a light beam having a wide luminous flux is incident on the lens. Therefore, the light rays are easily affected by the fifth lens L5 immediately after the aperture stop ST, and spherical aberration, coma aberration, axial chromatic aberration, and the like are particularly large. To reduce spherical aberration and coma, it is possible to increase the refractive index and loosen the radius of curvature of the lens surface, but since glass materials with a large refractive index generally have a large dispersion, axial chromatic aberration worsens. On the other hand, it is possible to reduce the axial chromatic aberration by reducing the dispersion, but since the refractive index becomes small, the radius of curvature must be tight, and the occurrence of spherical aberration and coma increases. .. By using a glass material that satisfies the conditional equations (10) and (11), axial chromatic aberration can be reduced while suppressing spherical aberration and coma, and good optical performance can be ensured. it can.

Further, in the imaging optical system 10, the lens on the most object side of the second lens group Gr2 further satisfies the following conditional expression (12).
2.0 ≤ f5 / F ≤ 4.5 ... (12)
However, the value f5 is the focal length of the lens located closest to the object side of the second lens group Gr2.

Conditional expression (12) is the ratio of the focal length of the lens located closest to the object side of the second lens group Gr2, that is, the fifth lens L5, to the focal length of the entire imaging optical system 10. The fifth lens L5, which is located on the most object side of the second lens group Gr2, is located immediately after the aperture stop ST, and a thick luminous flux passes through the lens, so that the contribution to the luminous flux is large. By setting the value f5 / F of the conditional expression (12) to the upper limit value or less, the focal length of the fifth lens L5 located closest to the object side in the second lens group Gr2 does not become too long, and the large size of the imaging optical system 10 It is possible to prevent the conversion. On the other hand, when the value is equal to or greater than the lower limit of the conditional expression (12), the focal length of the fifth lens L5 is not too short, and deterioration of spherical aberration and coma can be prevented. In addition, since the power is not made too strong, it is possible to suppress aberration fluctuations due to manufacturing errors and ensure mass productivity. Therefore, by satisfying the range of the conditional expression (12), the miniaturization of the imaging optical system 10, good optical performance, and mass productivity can be ensured.

Further, the imaging optical system 10 further satisfies the following conditional expression (13).
0.0 <Fb / L ≦ 0.2… (13)
However, the value Fb is the distance on the optical axis AX from the image side surface of the final lens to the imaging position, and the value L is the distance on the optical axis AX from the object side surface of the first lens L1 to the imaging position (however, The values L and Fb are air-equivalent lengths when a refractive index medium is present).

The conditional expression (13) is an expression that defines the length of the back focus with respect to the total optical length. By setting the value Fb / L of the conditional expression (13) to the upper limit value or less, the back focus is not made too long with respect to the optical total length, so that it is possible to prevent the optical total length from becoming large. On the other hand, by exceeding the lower limit of the conditional expression (13), it is possible to prevent the back focus from becoming excessively short, and even when dust adheres to the lens on the image side, the reflection of dust on the image is less noticeable. can do. Further, since the back focus can be secured to some extent, a space where an optical filter or the like can be inserted can be secured.

The imaging optical system 10 may further include other optical elements (for example, a lens, a filter member, etc.) having substantially no power.

In the imaging optical system or the like described above, the entrance pupil position can be positioned on the object side by locating the negative lens on the object side, so that the front lens diameter can be reduced. Further, by using two positive lenses and two negative lenses, the power of each lens can be relaxed as compared with the case of using one positive lens and one negative lens, so that aberrations generated in each lens can be relaxed. Can be suppressed. Further, by using the same number of positive lenses and negative lenses, it is possible to cancel out the aberrations generated in each lens, and it is possible to reduce the curvature of field and distortion in the periphery, which are particularly likely to occur in wide-angle lenses. Further, by using two positive lenses instead of one, the power of the lens can be relaxed, so that the aberration fluctuation due to the manufacturing error can be reduced and the mass productivity can be improved. Further, by appropriately arranging the plastic lens in the first lens group Gr1, the focus movement can be canceled by the refractive power of the opposite sign, so that the first lens group Gr1 when a temperature change occurs. It is possible to suppress the in-focus movement and aberration fluctuation within an appropriate range. Further, as in the case of the first lens group Gr1, the second lens group Gr2 can cancel the focus movement by the refractive power of the opposite sign by appropriately arranging the positive and negative plastic lenses. The amount of focus movement within the two lens group Gr2 can be suppressed to an appropriate range. As described above, by appropriately arranging a plastic lens having a positive refractive power and a plastic lens having a negative refractive power in each lens group Gr1 and Gr2, it is generated in each lens group Gr1 and Gr2 when the temperature changes. Since the focus movement and the aberration fluctuation can be kept within an appropriate range, the focus movement and the aberration fluctuation can be kept within an appropriate range even in the entire imaging optical system 10. By using a plastic lens in the first and second lens groups Gr1 and Gr2, the weight of the imaging optical system 10 can be reduced. In addition, since aspherical surfaces can be used frequently, aberrations can be satisfactorily corrected.

The lens unit 40 and the imaging device 10 incorporating the above-mentioned imaging optical system 10 enable imaging in a state where the angle of view is wide, inexpensive, and good optical performance is ensured.

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ ：基準曲率半径
Ｋ ：円錐定数〔Example〕
Hereinafter, examples of the imaging optical system and the like of the present invention will be shown. The symbols used in each embodiment are as follows.
f: Focal length of the entire imaging optical system Fno: F number w: Half angle of view ymax: Maximum image height TL: Total length of lens (distance on the optical axis from the lens surface on the most object side to the imaging surface)
PDΔ + 100: Focus movement amount due to temperature change of plastic lens from room temperature (20 ° C) to 100 ° C high temperature PDΔ-65: Focus movement amount due to temperature change of plastic lens from room temperature (20 ° C) to 65 ° C low temperature R: Radius of curvature D: Shaft top surface spacing eff. rad. : Effective radius nd: Refractive index of lens material with respect to d-line vd: Abbe number of lens material In each embodiment, the surface in which "*" is described after each surface number is a surface having an aspherical shape and is not. The shape of the spherical surface is represented by the following "Equation 1" with the apex of the surface as the origin, the X-axis in the optical axis direction, and the height in the direction perpendicular to the optical axis as h.

However,
Ai: i-order aspherical coefficient R: reference radius of curvature K: conical constant

(Example 1)
The overall specifications of the imaging optical system of Example 1 are shown below.
f: 0.84 (mm)
Fno: 1.99
w: 100.0 (°)
ymax: 1.84 (mm)
TL: 19.54 (mm)
PDΔ + 100: 0.0 (μm)
PDΔ-65: -0.8 (μm)

The data of the lens surface of the imaging optical system of Example 1 is shown in Table 1 below. In Table 1 and the like below, the surface number is represented by "Surf. N", the aperture stop is represented by "ST", and infinity is represented by "INF".
[Table 1]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 20.000 2.50 11.078 1.72916 54.7
2 5.203 4.08 4.957
3 * -8.321 0.71 3.588 1.54438 55.9
4 * 1.509 2.00 2.042
5 * 6.106 1.76 1.941 1.63469 23.9
6 * -10.400 0.26 1.536
7 * -5.980 1.92 1.512 1.54438 55.9
8 * -2.757 0.98 1.300
9 ST INF 0.20 0.776
10 5.017 1.42 0.835 1.72916 54.7
11 -2.134 0.10 0.939
12 * -1.974 0.45 0.927 1.63469 23.9
13 * 2.801 0.26 1.030
14 * 2.971 1.10 1.266 1.54438 55.9
15 * -2.584 0.96 1.430
16 INF 0.70 1.710 1.51680 64.0
17 INF 0.14 1.804

The aspherical coefficients of the lens surface of Example 1 are shown in Table 2 below. In the following it (including lens data in Tables), and represents an exponent of 10 (for example, 2.5 × ^{10 -02)} with E (e.g. 2.5E-02).
[Table 2]
Third side
K = -50.000, A3 = 1.8697E-02, A4 = 1.9301E-02, A5 = 1.2271E-04,
A6 = -3.7715E-03, A7 = 3.9000E-05, A8 = 2.2534E-04, A9 = -2.0000E-06,
A10 = -5.00E-06, A11 = -7.2830E-08, A12 = 2.6580E-08, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -0.659, A3 = -3.3934E-02, A4 = 3.9438E-02, A5 = 2.4686E-03,
A6 = 9.3075E-03, A7 = -9.8364E-04, A8 = -2.1815E-03, A9 = 5.5000E-05,
A10 = -6.7812E-04, A11 = 3.2000E-05, A12 = 1.0921E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -59.852, A3 = 0.000E + 00, A4 = 3.5245E-03, A5 = 0.000E + 00,
A6 = 4.6005E-03, A7 = 0.000E + 00, A8 = -3.7101E-04, A9 = 0.000E + 00,
A10 = -8.7000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = 25.756, A3 = 0.000E + 00, A4 = 8.9415E-03, A5 = 0.000E + 00,
A6 = 1.6607E-02, A7 = 0.000E + 00, A8 = -4.3929E-03, A9 = 0.000E + 00,
A10 = 5.2797E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -10.285, A3 = 0.000E + 00, A4 = 6.0512E-03, A5 = 0.000E + 00,
A6 = 2.3644E-03, A7 = 0.000E + 00, A8 = -1.9557E-03, A9 = 0.000E + 00,
A10 = 3.9852E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = 0.047, A3 = 0.000E + 00, A4 = 1.7068E-03, A5 = 0.000E + 00,
A6 = -7.3218E-04, A7 = 0.000E + 00, A8 = 3.7586E-04, A9 = 0.000E + 00,
A10 = -5.3000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 1.658, A3 = 0.000E + 00, A4 = -2.8576E-02, A5 = 0.000E + 00,
A6 = 5.7440E-02, A7 = 0.000E + 00, A8 = -2.1242E-02, A9 = 0.000E + 00,
A10 = -3.6782E-03, A11 = 0.000E + 00, A12 = 1.6001E-02, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = 1.123, A3 = 0.000E + 00, A4 = -8.4925E-02, A5 = 0.000E + 00,
A6 = 5.0238E-02, A7 = 0.000E + 00, A8 = -2.5685E-02, A9 = 0.000E + 00,
A10 = 2.6685E-03, A11 = 0.000E + 00, A12 = 1.0534E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 0.444, A3 = 0.000E + 00, A4 = -3.6392E-02, A5 = 0.000E + 00,
A6 = -1.9949E-03, A7 = 0.000E + 00, A8 = 5.1362E-03, A9 = 0.000E + 00,
A10 = -1.0195E-03, A11 = 0.000E + 00, A12 = -5.7271E-04, A13 = 0.000E + 00,
A14 = 5.4000E-05
Page 15
K = 0.632, A3 = 0.000E + 00, A4 = 3.3360E-02, A5 = 0.000E + 00,
A6 = -1.5096E-02, A7 = 0.000E + 00, A8 = -3.3000E-05, A9 = 0.000E + 00,
A10 = 3.3871E-03, A11 = 0.000E + 00, A12 = -6.5761E-04, A13 = 0.000E + 00,
A14 = -7.8000E-05

The focal lengths of each lens of Example 1 are shown in Table 3 below.
[Table 3]
Lens focal length (mm)
L1 -10.3851
L2 -2.2881
L3 6.3229
L4 7.7659
L5 2.2404
L6 -1.7603
L7 2.7187

FIG. 2A is a cross-sectional view of the imaging optical system 10A and the like according to the first embodiment. The imaging optical system 10A includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, and a third lens L3 having a positive refractive power as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10A includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group 2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51. The filter F is a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of the image sensor 51, and the like. Reference numeral I indicates an image pickup surface which is a projection plane of the image pickup device 51. The same applies to the reference numerals F and I in the following examples.

2B and 2C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10A of the first embodiment.

(Example 2)
The overall specifications of the imaging optical system of Example 2 are shown below.
f: 0.82 (mm)
Fno: 1.99
w: 100.0 (°)
ymax: 1.84 (mm)
TL: 19.05 (mm)
PDΔ + 100: 10.2 (μm)
PDΔ-65: -7.2 (μm)

The data of the lens surface of the imaging optical system of Example 2 is shown in Table 4 below.
[Table 4]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 20.000 2.50 10.393 1.77250 49.6
2 4.703 3.62 4.519
3 * -7.592 0.90 3.602 1.54438 55.9
4 * 2.148 1.96 2.122
5 * 6.011 1.50 1.982 1.63469 23.9
6 * -37.237 0.38 1.603
7 * -7.840 2.51 1.568 1.54438 55.9
8 * -2.492 0.78 1.200
9 ST INF 0.45 0.731
10 5.412 0.77 0.880 1.72916 54.7
11 -2.537 0.10 0.924
12 * -2.184 0.40 0.915 1.63469 23.9
13 * 2.772 0.24 1.000
14 * 2.996 0.95 1.149 1.54438 55.9
15 * -2.307 1.04 1.250
16 INF 0.70 1.631 1.51680 64.0
17 INF 0.23 1.766

The aspherical coefficients of the lens surface of Example 2 are shown in Table 5 below.
[Table 5]
Third side
K = -50.000, A3 = 2.4065E-02, A4 = 2.0172E-02, A5 = -9.3000E-05,
A6 = -3.8353E-03, A7 = 3.1000E-05, A8 = 2.2510E-04, A9 = -2.0000E-06,
A10 = -5.00E-06, A11 = -6.0201E-08, A12 = 2.5220E-08, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -0.615, A3 = 1.6245E-02, A4 = 4.3248E-02, A5 = 1.6619E-03,
A6 = 8.2185E-03, A7 = -1.1121E-03, A8 = -2.0476E-03, A9 = 1.3413E-04,
A10 = -6.4847E-04, A11 = 3.0000E-05, A12 = 1.0202E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -34.030, A3 = 0.000E + 00, A4 = 1.6259E-02, A5 = 0.000E + 00,
A6 = 4.2164E-03, A7 = 0.000E + 00, A8 = -4.5069E-04, A9 = 0.000E + 00,
A10 = -9.9000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = 66.908, A3 = 0.000E + 00, A4 = 6.0410E-03, A5 = 0.000E + 00,
A6 = 1.6459E-02, A7 = 0.000E + 00, A8 = -4.5313E-03, A9 = 0.000E + 00,
A10 = 4.4606E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -3.428, A3 = 0.000E + 00, A4 = 9.5107E-04, A5 = 0.000E + 00,
A6 = 2.7488E-03, A7 = 0.000E + 00, A8 = -1.4421E-03, A9 = 0.000E + 00,
A10 = 3.9228E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.357, A3 = 0.000E + 00, A4 = 8.7187E-03, A5 = 0.000E + 00,
A6 = -8.5035E-04, A7 = 0.000E + 00, A8 = 2.8453E-04, A9 = 0.000E + 00,
A10 = -3.1000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 2.121, A3 = 0.000E + 00, A4 = -1.4694E-02, A5 = 0.000E + 00,
A6 = 5.7173E-02, A7 = 0.000E + 00, A8 = -2.2720E-02, A9 = 0.000E + 00,
A10 = 3.5433E-03, A11 = 0.000E + 00, A12 = 8.4987E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = 0.357, A3 = 0.000E + 00, A4 = -8.7647E-02, A5 = 0.000E + 00,
A6 = 4.4154E-02, A7 = 0.000E + 00, A8 = -2.4975E-02, A9 = 0.000E + 00,
A10 = 3.6607E-03, A11 = 0.000E + 00, A12 = 8.3811E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 1.394, A3 = 0.000E + 00, A4 = -2.8923E-02, A5 = 0.000E + 00,
A6 = 2.2345E-03, A7 = 0.000E + 00, A8 = 4.4833E-03, A9 = 0.000E + 00,
A10 = -1.7475E-03, A11 = 0.000E + 00, A12 = -7.5495E-04, A13 = 0.000E + 00,
A14 = 1.5864E-04
Page 15
K = 0.101, A3 = 0.000E + 00, A4 = 5.5595E-02, A5 = 0.000E + 00,
A6 = -1.8969E-03, A7 = 0.000E + 00, A8 = 1.6262E-03, A9 = 0.000E + 00,
A10 = 3.1881E-03, A11 = 0.000E + 00, A12 = -9.3278E-04, A13 = 0.000E + 00,
A14 = -1.9248E-04

The focal lengths of each lens of Example 2 are shown in Table 6 below.
[Table 6]
Lens focal length (mm)
L1 -8.5696
L2 -2.9785
L3 8.2653
L4 5.7569
L5 2.4696
L6 -1.8663
L7 2.5460

FIG. 3A is a cross-sectional view of the imaging optical system 10B and the like according to the second embodiment. The imaging optical system 10B includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a positive lens group Gr1 as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10B includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

3B and 3C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10B of the second embodiment.

(Example 3)
The overall specifications of the imaging optical system of Example 3 are shown below.
f: 0.54 (mm)
Fno: 2.00
w: 100.0 (°)
ymax: 1.88 (mm)
TL: 20.94 (mm)
PDΔ + 100: 4.1 (μm)
PDΔ-65: -3.3 (μm)

The data of the lens surface of the imaging optical system of Example 3 is shown in Table 7 below.
[Table 7]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 20.000 2.50 10.918 1.77250 49.6
2 4.024 4.10 4.024
3 * -4.623 1.01 3.508 1.54438 55.9
4 * 1.769 2.04 2.442
5 * 4.411 2.51 2.294 1.63469 23.9
6 * -14.506 0.40 1.617
7 * -4.630 2.51 1.571 1.54438 55.9
8 * -2.700 1.22 1.142
9 ST INF 0.20 0.628
10 3.685 0.61 0.741 1.72916 54.7
11 -2.993 0.17 0.796
12 * -1.945 0.40 0.799 1.63469 23.9
13 * 2.889 0.19 0.925
14 * 2.444 1.56 1.090 1.54438 55.9
15 * -1.687 0.70 1.207
16 INF 0.70 1.630 1.51680 64.0
17 INF 0.10 1.831

The aspherical coefficients of the lens surface of Example 3 are shown in Table 8 below.
[Table 8]
Third side
K = -50.000, A3 = 8.1830E-02, A4 = -4.2231E-03, A5 = 2.7729E-03,
A6 = -5.4273E-03, A7 = -1.5000E-05, A8 = 5.1687E-04, A9 = 4.8000E-05,
A10 = -4.4000E-05, A11 = 1.0000E-06, A12 = 1.0000E-06, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -0.638, A3 = -1.7509E-02, A4 = 1.4754E-01, A5 = -8.7406E-02,
A6 = 6.5340E-03, A7 = 2.3017E-03, A8 = -4.3758E-04, A9 = 8.9566E-04,
A10 = -4.2021E-04, A11 = 1.3000E-05, A12 = 1.1000E-05, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -25.381, A3 = 0.000E + 00, A4 = 1.5533E-02, A5 = 0.000E + 00,
A6 = 3.6298E-03, A7 = 0.000E + 00, A8 = -1.2182E-03, A9 = 0.000E + 00,
A10 = 8.9000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = 49.966, A3 = 0.000E + 00, A4 = 2.5904E-02, A5 = 0.000E + 00,
A6 = 2.2617E-02, A7 = 0.000E + 00, A8 = -1.1630E-02, A9 = 0.000E + 00,
A10 = 1.7400E-03, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -8.614, A3 = 0.000E + 00, A4 = 2.8555E-02, A5 = 0.000E + 00,
A6 = -2.7108E-04, A7 = 0.000E + 00, A8 = -3.5413E-03, A9 = 0.000E + 00,
A10 = 7.2013E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.731, A3 = 0.000E + 00, A4 = 1.0996E-02, A5 = 0.000E + 00,
A6 = -4.1720E-03, A7 = 0.000E + 00, A8 = 1.0746E-03, A9 = 0.000E + 00,
A10 = -1.2866E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = -0.030, A3 = 0.000E + 00, A4 = 3.1914E-02, A5 = 0.000E + 00,
A6 = 4.8913E-02, A7 = 0.000E + 00, A8 = -2.9109E-01, A9 = 0.000E + 00,
A10 = 6.4918E-01, A11 = 0.000E + 00, A12 = -5.1763E-01, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = 3.876, A3 = 0.000E + 00, A4 = -4.2033E-02, A5 = 0.000E + 00,
A6 = 1.3278E-03, A7 = 0.000E + 00, A8 = -3.4698E-02, A9 = 0.000E + 00,
A10 = 8.8179E-02, A11 = 0.000E + 00, A12 = -6.6674E-02, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 1.730, A3 = 0.000E + 00, A4 = -4.2424E-02, A5 = 0.000E + 00,
A6 = 1.2231E-03, A7 = 0.000E + 00, A8 = 2.4729E-02, A9 = 0.000E + 00,
A10 = -2.3210E-02, A11 = 0.000E + 00, A12 = 1.2083E-02, A13 = 0.000E + 00,
A14 = -3.6867E-03
Page 15
K = 0.146, A3 = 0.000E + 00, A4 = 1.7992E-01, A5 = 0.000E + 00,
A6 = -9.2916E-02, A7 = 0.000E + 00, A8 = 6.0128E-02, A9 = 0.000E + 00,
A10 = 2.1946E-03, A11 = 0.000E + 00, A12 = -1.5487E-02, A13 = 0.000E + 00,
A14 = 5.7999E-03

The focal lengths of each lens of Example 3 are shown in Table 9 below.
[Table 9]
Lens focal length (mm)
L1 -6.9982
L2 -2.2257
L3 5.6183
L4 8.1612
L5 2.3561
L6 -1.7744
L7 2.1077

FIG. 4A is a cross-sectional view of the imaging optical system 10C and the like according to the third embodiment. The imaging optical system 10C includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, and a third lens L3 having a positive refractive power as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10C includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

4B and 4C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10C of the third embodiment.

(Example 4)
The overall specifications of the imaging optical system of Example 4 are shown below.
f: 0.72 (mm)
Fno: 1.83
w: 100.0 (°)
ymax: 1.87 (mm)
TL: 18.96 (mm)
PDΔ + 100: 6.7 (μm)
PDΔ-65: -4.8 (μm)

The data of the lens surface of the imaging optical system of Example 4 is shown in Table 10 below.
[Table 10]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 19.000 2.50 11.000 1.77250 49.6
2 4.091 4.05 4.091
3 * -4.056 0.70 3.510 1.54438 55.9
4 * 3.992 2.16 2.294
5 * 7.926 2.51 2.235 1.63469 23.9
6 * -4.384 0.16 1.592
7 * -3.899 2.51 1.588 1.54438 55.9
8 * -2.312 0.20 1.057
9 ST INF 0.20 0.757
10 4.850 0.66 0.881 1.72916 54.7
11 -2.473 0.10 0.942
12 * -2.242 0.40 0.939 1.63469 23.9
13 * 2.073 0.23 1.075
14 * 2.707 0.84 1.414 1.54438 55.9
15 * -2.524 0.93 1.293
16 INF 0.70 1.576 1.51680 64.0
17 INF 0.10 1.827

The aspherical coefficients of the lens surface of Example 4 are shown in Table 11 below.
[Table 11]
Third side
K = -50.000, A3 = 2.5200E-02, A4 = 2.8311E-02, A5 = -3.1389E-04,
A6 = -5.6985E-03, A7 = -7.2000E-05, A8 = 5.8061E-04, A9 = 1.0000E-06,
A10 = -4.6000E-05, A11 = 7.0000E-06, A12 = -1.7908E-07, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -0.328, A3 = 4.6996E-02, A4 = 8.5149E-02, A5 = -2.0797E-02,
A6 = 5.4769E-03, A7 = -6.8135E-04, A8 = -1.2800E-03, A9 = 6.7248E-04,
A10 = -5.7667E-04, A11 = 7.0000E-06, A12 = 5.9000E-05, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = 0.133, A3 = 0.000E + 00, A4 = 1.1418E-02, A5 = 0.000E + 00,
A6 = 2.6750E-03, A7 = 0.000E + 00, A8 = -5.5760E-04, A9 = 0.000E + 00,
A10 = 2.3000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = -26.418, A3 = 0.000E + 00, A4 = 3.6781E-02, A5 = 0.000E + 00,
A6 = 1.0135E-02, A7 = 0.000E + 00, A8 = -3.9910E-03, A9 = 0.000E + 00,
A10 = 6.2329E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -25.155, A3 = 0.000E + 00, A4 = 2.4447E-02, A5 = 0.000E + 00,
A6 = 4.9910E-03, A7 = 0.000E + 00, A8 = -4.5702E-03, A9 = 0.000E + 00,
A10 = 1.2126E-03, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.656, A3 = 0.000E + 00, A4 = 2.9589E-02, A5 = 0.000E + 00,
A6 = -1.1742E-02, A7 = 0.000E + 00, A8 = 7.1743E-03, A9 = 0.000E + 00,
A10 = -3.0632E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 3.137, A3 = 0.000E + 00, A4 = 1.9158E-02, A5 = 0.000E + 00,
A6 = 3.6250E-02, A7 = 0.000E + 00, A8 = -5.2294E-02, A9 = 0.000E + 00,
A10 = 1.1628E-01, A11 = 0.000E + 00, A12 = -5.1485E-02, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = -1.166, A3 = 0.000E + 00, A4 = -6.7107E-02, A5 = 0.000E + 00,
A6 = 4.9823E-03, A7 = 0.000E + 00, A8 = -1.0472E-03, A9 = 0.000E + 00,
A10 = 5.1949E-03, A11 = 0.000E + 00, A12 = -8.5136E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 2.335, A3 = 0.000E + 00, A4 = 6.6305E-03, A5 = 0.000E + 00,
A6 = 2.4425E-03, A7 = 0.000E + 00, A8 = -2.9569E-03, A9 = 0.000E + 00,
A10 = -8.2964E-04, A11 = 0.000E + 00, A12 = 1.4386E-03, A13 = 0.000E + 00,
A14 = -2.9428E-04
Page 15
K = -1.942, A3 = 0.000E + 00, A4 = 8.5423E-02, A5 = 0.000E + 00,
A6 = 8.8825E-03, A7 = 0.000E + 00, A8 = 2.4551E-02, A9 = 0.000E + 00,
A10 = -5.9765E-03, A11 = 0.000E + 00, A12 = -8.8743E-03, A13 = 0.000E + 00,
A14 = 4.6954E-03

The focal lengths of each lens of Example 4 are shown in Table 12 below.
[Table 12]
Lens focal length (mm)
L1 -7.2819
L2 -3.5855
L3 4.8300
L4 6.6987
L5 2.3359
L6 -1.6379
L7 2.5339

FIG. 5A is a cross-sectional view of the imaging optical system 10D and the like according to the fourth embodiment. The imaging optical system 10D includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a positive lens group Gr1 as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10D includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

5B and 5C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10D of Example 4.

(Example 5)
The overall specifications of the imaging optical system of Example 5 are shown below.
f: 0.70 (mm)
Fno: 2.00
w: 100.0 (°)
ymax: 1.86 (mm)
TL: 18.57 (mm)
PDΔ + 100: 5.8 (μm)
PDΔ-65: -4.3 (μm)

The data of the lens surface of the imaging optical system of Example 5 is shown in Table 13 below.
[Table 13]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 19.000 2.50 10.781 1.77250 49.6
2 3.869 3.87 3.869
3 * -3.998 0.70 3.277 1.54438 55.9
4 * 5.171 1.91 2.192
5 * 15.473 2.51 2.128 1.63469 23.9
6 * -2.716 0.13 1.504
7 * -2.519 2.51 1.480 1.54438 55.9
8 * -2.372 0.20 0.802
9 ST INF 0.20 0.671
10 4.870 0.66 0.755 1.72916 54.7
11 -2.492 0.10 0.809
12 * -2.106 0.40 0.806 1.63469 23.9
13 * 2.182 0.22 0.900
14 * 2.719 0.87 1.050 1.54438 55.9
15 * -2.103 0.93 1.110
16 INF 0.70 1.580 1.51680 64.0
17 INF 0.17 1.784

The aspherical coefficients of the lens surface of Example 5 are shown in Table 14 below.
[Table 14]
Third side
K = -50.000, A3 = 4.8374E-02, A4 = 2.4765E-02, A5 = -2.6671E-04,
A6 = -5.8927E-03, A7 = -8.4000E-05, A8 = 5.7466E-04, A9 = 3.0000E-06,
A10 = -4.5000E-05, A11 = 7.0000E-06, A12 = -2.3863E-07, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = 1.096, A3 = 7.1506E-02, A4 = 8.7186E-02, A5 = -1.7704E-02,
A6 = 4.0197E-03, A7 = -1.7740E-03, A8 = -1.3755E-03, A9 = 6.9799E-04,
A10 = -5.4279E-04, A11 = 1.9000E-05, A12 = 6.0000E-05, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -0.104, A3 = 0.000E + 00, A4 = 1.7379E-02, A5 = 0.000E + 00,
A6 = 4.6884E-04, A7 = 0.000E + 00, A8 = -2.9413E-04, A9 = 0.000E + 00,
A10 = 1.3000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = -17.590, A3 = 0.000E + 00, A4 = 2.9467E-02, A5 = 0.000E + 00,
A6 = 4.2013E-03, A7 = 0.000E + 00, A8 = -4.0398E-03, A9 = 0.000E + 00,
A10 = 1.2669E-03, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -19.369, A3 = 0.000E + 00, A4 = 1.6467E-02, A5 = 0.000E + 00,
A6 = 3.6510E-03, A7 = 0.000E + 00, A8 = -3.7395E-03, A9 = 0.000E + 00,
A10 = 1.4642E-03, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.694, A3 = 0.000E + 00, A4 = 3.0878E-02, A5 = 0.000E + 00,
A6 = -1.1429E-02, A7 = 0.000E + 00, A8 = 7.1239E-03, A9 = 0.000E + 00,
A10 = -5.9042E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 2.959, A3 = 0.000E + 00, A4 = 2.5197E-02, A5 = 0.000E + 00,
A6 = 4.8953E-02, A7 = 0.000E + 00, A8 = -9.5059E-02, A9 = 0.000E + 00,
A10 = 2.2380E-01, A11 = 0.000E + 00, A12 = -1.2473E-01, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = -1.040, A3 = 0.000E + 00, A4 = -6.6743E-02, A5 = 0.000E + 00,
A6 = -1.7087E-02, A7 = 0.000E + 00, A8 = 1.7542E-02, A9 = 0.000E + 00,
A10 = 3.8037E-03, A11 = 0.000E + 00, A12 = -6.3571E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 2.362, A3 = 0.000E + 00, A4 = 1.8274E-02, A5 = 0.000E + 00,
A6 = -2.8170E-04, A7 = 0.000E + 00, A8 = -3.2745E-03, A9 = 0.000E + 00,
A10 = -3.8435E-04, A11 = 0.000E + 00, A12 = 2.5394E-03, A13 = 0.000E + 00,
A14 = -8.6080E-04
Page 15
K = -3.095, A3 = 0.000E + 00, A4 = 7.9135E-02, A5 = 0.000E + 00,
A6 = 1.2887E-02, A7 = 0.000E + 00, A8 = 3.8062E-02, A9 = 0.000E + 00,
A10 = -9.8895E-03, A11 = 0.000E + 00, A12 = -1.3574E-02, A13 = 0.000E + 00,
A14 = 7.2716E-03

The focal lengths of each lens of Example 5 are shown in Table 15 below.
[Table 15]
Lens focal length (mm)
L1 -6.7766
L2 -4.0333
L3 3.8460
L4 10.6353
L5 2.3497
L6 -1.6295
L7 2.3161

FIG. 6A is a cross-sectional view of the imaging optical system 10E and the like according to the fifth embodiment. The imaging optical system 10E includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, and a third lens L3 having a positive refractive power as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10E includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

6B and 6C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10E of Example 5.

(Example 6)
The overall specifications of the imaging optical system of Example 6 are shown below.
f: 0.72 (mm)
Fno: 1.99
w: 100.0 (°)
ymax: 1.83 (mm)
TL: 17.66 (mm)
PDΔ + 100: 12.8 (μm)
PDΔ-65: -8.5 (μm)

The data of the lens surface of the imaging optical system of Example 6 is shown in Table 16 below.
[Table 16]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 19.000 2.50 9.508 1.77250 49.6
2 3.293 2.84 3.293
3 * -8.644 0.70 3.160 1.54438 55.9
4 * 6.516 1.64 2.486
5 * 3.708 2.51 2.320 1.63469 23.9
6 * 6.456 0.34 1.741
7 * -10.061 1.39 1.675 1.54438 55.9
8 * -3.033 0.87 1.302
9 ST INF 0.50 0.458
10 13.490 0.86 0.833 1.72916 54.7
11 -2.000 0.10 1.012
12 * -12.875 0.40 1.029 1.63469 23.9
13 * 3.032 0.26 1.282
14 * -2.437 1.26 1.390 1.54438 55.9
15 * -0.791 0.60 1.451
16 INF 0.70 1.706 1.51680 64.0
17 INF 0.20 1.794

The aspherical coefficients of the lens surface of Example 6 are shown in Table 17 below.
[Table 17]
Third side
K = 4.215, A3 = -5.4339E-04, A4 = 3.2110E-02, A5 = 4.2523E-03,
A6 = -5.2070E-03, A7 = -1.6994E-04, A8 = 5.2299E-04, A9 = -6.00E-06,
A10 = -4.4000E-05, A11 = 7.0000E-06, A12 = -2.8997E-07, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -13.696, A3 = -2.8757E-02, A4 = 7.0697E-02, A5 = -2.1760E-02,
A6 = 7.990E-03, A7 = 6.6484E-04, A8 = -6.5989E-04, A9 = 9.5381E-04,
A10 = -6.2938E-04, A11 = -1.4000E-05, A12 = 3.9000E-05, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = 0.542, A3 = 0.000E + 00, A4 = 7.2782E-04, A5 = 0.000E + 00,
A6 = 2.7095E-03, A7 = 0.000E + 00, A8 = -1.1735E-03, A9 = 0.000E + 00,
A10 = 8.9000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = -5.780, A3 = 0.000E + 00, A4 = 4.4478E-03, A5 = 0.000E + 00,
A6 = 7.3008E-03, A7 = 0.000E + 00, A8 = -3.4235E-03, A9 = 0.000E + 00,
A10 = 3.7816E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -23.012, A3 = 0.000E + 00, A4 = 3.0402E-02, A5 = 0.000E + 00,
A6 = 7.3484E-03, A7 = 0.000E + 00, A8 = -3.1278E-03, A9 = 0.000E + 00,
A10 = 3.4053E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.884, A3 = 0.000E + 00, A4 = 4.4666E-02, A5 = 0.000E + 00,
A6 = -1.4394E-02, A7 = 0.000E + 00, A8 = 4.7763E-03, A9 = 0.000E + 00,
A10 = -5.4736E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = -42.497, A3 = 0.000E + 00, A4 = -2.9253E-01, A5 = 0.000E + 00,
A6 = 1.3887E-01, A7 = 0.000E + 00, A8 = -1.1445E-01, A9 = 0.000E + 00,
A10 = 9.8885E-02, A11 = 0.000E + 00, A12 = -3.3092E-02, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = -17.046, A3 = 0.000E + 00, A4 = -1.0270E-01, A5 = 0.000E + 00,
A6 = 4.4604E-02, A7 = 0.000E + 00, A8 = -6.9698E-03, A9 = 0.000E + 00,
A10 = -2.5803E-03, A11 = 0.000E + 00, A12 = 3.6186E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = -10.267, A3 = 0.000E + 00, A4 = 8.5878E-02, A5 = 0.000E + 00,
A6 = -4.4656E-03, A7 = 0.000E + 00, A8 = -4.1451E-03, A9 = 0.000E + 00,
A10 = 1.1863E-03, A11 = 0.000E + 00, A12 = 3.0000E-06, A13 = 0.000E + 00,
A14 = -4.0000E-06
Page 15
K = -0.810, A3 = 0.000E + 00, A4 = 2.4853E-01, A5 = 0.000E + 00,
A6 = -9.2429E-02, A7 = 0.000E + 00, A8 = 3.7925E-02, A9 = 0.000E + 00,
A10 = 3.3610E-03, A11 = 0.000E + 00, A12 = -3.7038E-03, A13 = 0.000E + 00,
A14 = 6.8361E-04

The focal lengths of each lens of Example 6 are shown in Table 18 below.
[Table 18]
Lens focal length (mm)
L1 -5.5408
L2 -6.7154
L3 10.1302
L4 7.4566
L5 2.4457
L6 -3.8297
L7 1.6848

FIG. 7A is a cross-sectional view of the imaging optical system 10F and the like according to the sixth embodiment. The imaging optical system 10F includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a positive lens group Gr1 as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10F includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

7B and 7C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10F of the sixth embodiment.

(Example 7)
The overall specifications of the imaging optical system of Example 7 are shown below.
f: 0.92 (mm)
Fno: 1.99
w: 100.0 (°)
ymax: 1.93 (mm)
TL: 17.41 (mm)
PDΔ + 100: 1.2 (μm)
PDΔ-65: -1.5 (μm)

The data of the lens surface of the imaging optical system of Example 7 is shown in Table 19 below.
[Table 19]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 20.000 2.50 9.317 1.77250 49.6
2 4.471 2.75 4.132
3 * -8.051 0.79 3.590 1.54438 55.9
4 * 2.077 1.96 2.114
5 * 4.785 1.25 1.914 1.63469 23.9
6 * -9.356 0.43 1.620
7 * -4.405 2.14 1.536 1.54438 55.9
8 * -2.628 0.57 1.150
9 ST INF 0.37 0.732
10 4.332 0.85 0.750 1.72916 54.7
11 -2.540 0.10 0.877
12 * -2.234 0.35 0.882 1.63469 23.9
13 * 3.149 0.34 1.039
14 * 3.549 1.40 1.279 1.54438 55.9
15 * -2.246 0.17 1.475
16 INF 0.70 1.610 1.51680 64.0
17 INF 0.76 1.729

The aspherical coefficients of the lens surface of Example 7 are shown in Table 20 below.
[Table 20]
Third side
K = -50.000, A3 = 1.7745E-02, A4 = 2.0429E-02, A5 = 6.7000E-05,
A6 = -3.7969E-03, A7 = 3.9000E-05, A8 = 2.2635E-04, A9 = -2.0000E-06,
A10 = -5.00E-06, A11 = -7.8180E-08, A12 = 1.7192E-08, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -0.654, A3 = 7.8187E-03, A4 = 3.5881E-02, A5 = 9.3702E-04,
A6 = 8.3873E-03, A7 = -9.5467E-04, A8 = -1.9892E-03, A9 = 1.5082E-04,
A10 = -6.4376E-04, A11 = 3.4000E-05, A12 = 1.0538E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -29.555, A3 = 0.000E + 00, A4 = 1.4160E-02, A5 = 0.000E + 00,
A6 = 4.0993E-03, A7 = 0.000E + 00, A8 = -4.2494E-04, A9 = 0.000E + 00,
A10 = -1.1537E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = 18.516, A3 = 0.000E + 00, A4 = 6.2114E-03, A5 = 0.000E + 00,
A6 = 1.7236E-02, A7 = 0.000E + 00, A8 = -4.5562E-03, A9 = 0.000E + 00,
A10 = 4.4924E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -10.005, A3 = 0.000E + 00, A4 = 6.4679E-04, A5 = 0.000E + 00,
A6 = 2.0408E-03, A7 = 0.000E + 00, A8 = -1.5315E-03, A9 = 0.000E + 00,
A10 = 3.8318E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.253, A3 = 0.000E + 00, A4 = 7.7508E-03, A5 = 0.000E + 00,
A6 = -1.1188E-03, A7 = 0.000E + 00, A8 = 4.5916E-04, A9 = 0.000E + 00,
A10 = -2.2000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 2.094, A3 = 0.000E + 00, A4 = -2.1320E-02, A5 = 0.000E + 00,
A6 = 4.5856E-02, A7 = 0.000E + 00, A8 = -2.0418E-02, A9 = 0.000E + 00,
A10 = 6.6247E-03, A11 = 0.000E + 00, A12 = 6.3697E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = 0.803, A3 = 0.000E + 00, A4 = -8.5423E-02, A5 = 0.000E + 00,
A6 = 4.9968E-02, A7 = 0.000E + 00, A8 = -2.5178E-02, A9 = 0.000E + 00,
A10 = 1.9614E-03, A11 = 0.000E + 00, A12 = 2.5883E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 0.937, A3 = 0.000E + 00, A4 = -3.6681E-02, A5 = 0.000E + 00,
A6 = 5.3489E-03, A7 = 0.000E + 00, A8 = 5.3209E-03, A9 = 0.000E + 00,
A10 = -2.1728E-03, A11 = 0.000E + 00, A12 = -9.9146E-04, A13 = 0.000E + 00,
A14 = 5.3680E-04
Page 15
K = 0.249, A3 = 0.000E + 00, A4 = 4.2403E-02, A5 = 0.000E + 00,
A6 = -1.6246E-03, A7 = 0.000E + 00, A8 = -7.1426E-04, A9 = 0.000E + 00,
A10 = 2.4756E-03, A11 = 0.000E + 00, A12 = -7.3172E-04, A13 = 0.000E + 00,
A14 = 8.5000E-05

The focal lengths of each lens of Example 7 are shown in Table 21 below.
[Table 21]
Lens focal length (mm)
L1 -8.0158
L2 -2.9512
L3 5.1654
L4 8.4038
L5 2.3159
L6 -2.0085
L7 2.7615

FIG. 8A is a cross-sectional view of the imaging optical system 10G and the like according to the seventh embodiment. The imaging optical system 10G includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, and a third lens L3 having a positive refractive power as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10G includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

8B and 8C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10G of Example 7.

(Example 8)
The overall specifications of the imaging optical system of Example 8 are shown below.
f: 1.01 (mm)
Fno: 2.00
w: 100.0 (°)
ymax: 1.81 (mm)
TL: 19.14 (mm)
PDΔ + 100: 15.0 (μm)
PDΔ-65: -10.3 (μm)

The data of the lens surface of the imaging optical system of Example 8 is shown in Table 22 below.
[Table 22]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 20.000 0.87 6.984 1.77250 49.6
2 3.453 3.00 3.418
3 * -8.965 0.87 3.325 1.54438 55.9
4 * 3.004 1.60 2.859
5 * 3.190 2.51 2.580 1.63469 23.9
6 * 7.105 0.95 1.637
7 * -5.085 2.51 1.569 1.54438 55.9
8 * -3.094 0.20 1.163
9 ST INF 0.20 0.999
10 17.862 0.89 1.095 1.72916 54.7
11 -2.940 0.10 1.210
12 * -3.580 0.40 1.212 1.63469 23.9
13 * 3.989 0.34 1.335
14 * 5.277 1.11 1.483 1.54438 55.9
15 * -2.772 1.85 1.600
16 INF 0.70 1.729 1.51680 64.0
17 INF 1.04 1.756

The aspherical coefficients of the lens surface of Example 8 are shown in Table 23 below.
[Table 23]
Third side
K = -50.000, A3 = 6.5842E-02, A4 = -1.6158E-02, A5 = 1.0721E-03,
A6 = -1.6007E-03, A7 = 3.0973E-04, A8 = 1.3413E-04, A9 = -2.5000E-05,
A10 = -9.0000E-06, A11 = 3.0000E-06, A12 = -2.8272E-07, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -1.179, A3 = 3.9938E-02, A4 = 2.9002E-02, A5 = -2.0234E-02,
A6 = 2.0919E-03, A7 = -9.9900E-04, A8 = -6.0309E-04, A9 = 1.0321E-03,
A10 = -3.4070E-04, A11 = 2.6000E-05, A12 = 2.000E-06, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -0.639, A3 = 0.000E + 00, A4 = 7.1691E-03, A5 = 0.000E + 00,
A6 = 8.3572E-04, A7 = 0.000E + 00, A8 = -9.7000E-05, A9 = 0.000E + 00,
A10 = 1.5000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = 12.523, A3 = 0.000E + 00, A4 = 1.6096E-02, A5 = 0.000E + 00,
A6 = 7.1643E-03, A7 = 0.000E + 00, A8 = -1.0724E-03, A9 = 0.000E + 00,
A10 = 7.4980E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = 1.578, A3 = 0.000E + 00, A4 = 4.8495E-03, A5 = 0.000E + 00,
A6 = 4.0514E-03, A7 = 0.000E + 00, A8 = -1.1625E-03, A9 = 0.000E + 00,
A10 = 2.9884E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -1.232, A3 = 0.000E + 00, A4 = 1.5959E-02, A5 = 0.000E + 00,
A6 = 1.5036E-03, A7 = 0.000E + 00, A8 = -1.2040E-03, A9 = 0.000E + 00,
A10 = 9.6321E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 4.161, A3 = 0.000E + 00, A4 = -3.0521E-02, A5 = 0.000E + 00,
A6 = 3.4064E-02, A7 = 0.000E + 00, A8 = -2.4754E-04, A9 = 0.000E + 00,
A10 = -6.9815E-03, A11 = 0.000E + 00, A12 = 2.3475E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = 1.081, A3 = 0.000E + 00, A4 = -8.9698E-02, A5 = 0.000E + 00,
A6 = 4.8460E-02, A7 = 0.000E + 00, A8 = -8.0180E-03, A9 = 0.000E + 00,
A10 = -2.7643E-03, A11 = 0.000E + 00, A12 = 8.4527E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 1.583, A3 = 0.000E + 00, A4 = -3.0178E-02, A5 = 0.000E + 00,
A6 = 1.7818E-03, A7 = 0.000E + 00, A8 = 9.1309E-03, A9 = 0.000E + 00,
A10 = -5.0713E-03, A11 = 0.000E + 00, A12 = 1.0941E-03, A13 = 0.000E + 00,
A14 = -1.2397E-04
Page 15
K = 0.439, A3 = 0.000E + 00, A4 = 1.8358E-02, A5 = 0.000E + 00,
A6 = -2.8682E-03, A7 = 0.000E + 00, A8 = 2.1553E-03, A9 = 0.000E + 00,
A10 = -7.3346E-04, A11 = 0.000E + 00, A12 = 2.0297E-04, A13 = 0.000E + 00,
A14 = -4.5000E-05

The focal lengths of each lens of Example 8 are shown in Table 24 below.
[Table 24]
Lens focal length (mm)
L1 -5.5301
L2 -4.0300
L3 7.3041
L4 10.0511
L5 3.5255
L6 -2.9131
L7 3.4943

FIG. 9A is a cross-sectional view of the imaging optical system 10H and the like according to the eighth embodiment. The imaging optical system 10H includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a positive lens group Gr1 as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10H includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

9B and 9C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10H of Example 8.

(Example 9)
The overall specifications of the imaging optical system of Example 9 are shown below.
f: 0.81 (mm)
Fno: 2.00
w: 109.0 (°)
ymax: 1.88 (mm)
TL: 18.04 (mm)
PDΔ + 100: 12.3 (μm)
PDΔ-65: -8.6 (μm)

The data of the lens surface of the imaging optical system of Example 9 is shown in Table 25 below.
[Table 25]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 25.000 0.10 12.317 1.77250 49.6
2 20.509 1.70 8.369
3 * 4.664 2.92 4.210 1.54438 55.9
4 * -5.986 0.70 3.557
5 * 2.061 2.21 2.172 1.63469 23.9
6 * 6.165 1.23 1.951
7 * -9.036 0.38 1.720 1.54438 55.9
8 * -4.473 2.50 1.635
9 ST -2.63E + 00 0.51 1.100
10 INF 0.30 0.757 1.72916 54.7
11 13.266 1.55 0.892
12 * -2.220 0.10 1.138 1.63469 23.9
13 * -2.374 0.50 1.131
14 * 4.044 0.22 1.297 1.54438 55.9
15 * 3.710 1.22 1.419
16 -2.26E + 00 1.06 1.516 1.51680 64.0
17 INF 0.94 1.756

The aspherical coefficients of the lens surface of Example 9 are shown in Table 26 below.
[Table 26]
Third side
K = -38.700, A3 = -1.5345E-03, A4 = 2.7551E-02, A5 = 1.7629E-04,
A6 = -3.9429E-03, A7 = 6.0000E-06, A8 = 2.2765E-04, A9 = -1.0000E-06,
A10 = -5.00E-06, A11 = -4.080E-08, A12 = 3.7115E-08, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -0.574, A3 = -2.1058E-02, A4 = 3.7148E-02, A5 = 1.9244E-04,
A6 = 1.0811E-02, A7 = -1.2082E-04, A8 = -1.8374E-03, A9 = 4.0000E-05,
A10 = -7.3068E-04, A11 = 6.0000E-06, A12 = 1.1220E-04, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -50.000, A3 = 0.000E + 00, A4 = 1.5392E-02, A5 = 0.000E + 00,
A6 = 4.4394E-03, A7 = 0.000E + 00, A8 = -6.0678E-04, A9 = 0.000E + 00,
A10 = -8.7000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = 14.352, A3 = 0.000E + 00, A4 = -2.1136E-03, A5 = 0.000E + 00,
A6 = 1.4464E-02, A7 = 0.000E + 00, A8 = -4.4112E-03, A9 = 0.000E + 00,
A10 = 4.7948E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -2.642, A3 = 0.000E + 00, A4 = -1.0624E-02, A5 = 0.000E + 00,
A6 = 4.1989E-03, A7 = 0.000E + 00, A8 = -8.1333E-04, A9 = 0.000E + 00,
A10 = 1.9773E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.470, A3 = 0.000E + 00, A4 = 1.4546E-02, A5 = 0.000E + 00,
A6 = -1.2857E-03, A7 = 0.000E + 00, A8 = 1.0361E-03, A9 = 0.000E + 00,
A10 = -2.1488E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 2.080, A3 = 0.000E + 00, A4 = -1.6633E-02, A5 = 0.000E + 00,
A6 = 4.5825E-02, A7 = 0.000E + 00, A8 = -2.2799E-02, A9 = 0.000E + 00,
A10 = 3.5410E-03, A11 = 0.000E + 00, A12 = 4.2802E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = 1.212, A3 = 0.000E + 00, A4 = -6.5892E-02, A5 = 0.000E + 00,
A6 = 3.6833E-02, A7 = 0.000E + 00, A8 = -1.2455E-02, A9 = 0.000E + 00,
A10 = -2.0211E-03, A11 = 0.000E + 00, A12 = 1.4893E-03, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 0.818, A3 = 0.000E + 00, A4 = -3.2270E-02, A5 = 0.000E + 00,
A6 = 1.4958E-02, A7 = 0.000E + 00, A8 = -3.8695E-04, A9 = 0.000E + 00,
A10 = -1.5685E-03, A11 = 0.000E + 00, A12 = -1.3000E-05, A13 = 0.000E + 00,
A14 = 2.7000E-05
Page 15
K = 0.216, A3 = 0.000E + 00, A4 = 5.8886E-02, A5 = 0.000E + 00,
A6 = -7.7830E-03, A7 = 0.000E + 00, A8 = 3.5272E-03, A9 = 0.000E + 00,
A10 = 2.1820E-03, A11 = 0.000E + 00, A12 = -1.4191E-03, A13 = 0.000E + 00,
A14 = 1.6823E-04

The focal lengths of each lens of Example 9 are shown in Table 27 below.
[Table 27]
Lens focal length (mm)
L1 -8.1990
L2 -2.7326
L3 5.9616
L4 7.9107
L5 2.7232
L6 -2.2874
L7 2.7811

FIG. 10A is a cross-sectional view of the imaging optical system 10I and the like according to the ninth embodiment. The imaging optical system 10I includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, and a third lens L3 having a positive refractive power as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10I includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. To be equipped with. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, and seventh lenses L2, L3, L4, L6, and L7 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the seventh lens L7 and the image sensor 51.

10B and 10C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10I of the ninth embodiment.

(Example 10)
The overall specifications of the imaging optical system of Example 10 are shown below.
f: 0.65 (mm)
Fno: 2.00
w: 100.0 (°)
ymax: 1.85 (mm)
TL: 19.00 (mm)
PDΔ + 100: 1.5 (μm)
PDΔ-65: -1.6 (μm)

The data of the lens surface of the imaging optical system of Example 10 is shown in Table 28 below.
[Table 28]
Surf. NR (mm) D (mm) eff.rad. (mm) nd vd
1 20.000 2.50 9.711 1.77250 49.6
2 3.512 2.71 3.511
3 * -5.101 0.78 3.340 1.54438 55.9
4 * 2.516 2.20 2.305
5 * 6.347 2.40 2.196 1.63469 23.9
6 * -8.697 0.31 1.732
7 * -5.212 2.30 1.665 1.54438 55.9
8 * -2.907 1.33 1.300
9 ST INF 0.20 0.627
10 3.560 0.66 0.738 1.72916 54.7
11 -2.759 0.10 0.793
12 * -2.147 0.40 0.792 1.63469 23.9
13 * 2.967 0.30 0.895
14 * 2.717 0.79 1.064 1.54438 55.9
15 * -6.233 0.24 1.100
16 * -6.613 0.57 1.222 1.54438 55.9
17 * -1.688 0.50 1.349
18 INF 0.50 1.618 1.51680 64.0
19 INF 0.20 1.759

The aspherical coefficients of the lens surface of Example 10 are shown in Table 29 below.
[Table 29]
Third side
K = -50.000, A3 = 1.9590E-02, A4 = 1.8939E-02, A5 = 2.5559E-03,
A6 = -3.3619E-03, A7 = 4.3000E-05, A8 = 1.9624E-04, A9 = -1.0000E-05,
A10 = -6.0000E-06, A11 = -9.5300E-08, A12 = 1.2400E-07, A13 = 0.000E + 00,
A14 = 0.000E + 00
4th side
K = -2.366, A3 = 1.1442E-02, A4 = 3.0857E-02, A5 = 2.5314E-03,
A6 = 8.8577E-03, A7 = -3.4413E-04, A8 = -1.2617E-03, A9 = 5.2843E-04,
A10 = -5.3129E-04, A11 = 1.3000E-05, A12 = 4.0000E-05, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 5
K = -50.000, A3 = 0.000E + 00, A4 = 6.2397E-03, A5 = 0.000E + 00,
A6 = 2.6364E-03, A7 = 0.000E + 00, A8 = -9.1383E-04, A9 = 0.000E + 00,
A10 = 7.4000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
Side 6
K = 13.199, A3 = 0.000E + 00, A4 = 1.2010E-02, A5 = 0.000E + 00,
A6 = 1.0299E-02, A7 = 0.000E + 00, A8 = -3.9571E-03, A9 = 0.000E + 00,
A10 = 4.7288E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
7th page
K = -2.033, A3 = 0.000E + 00, A4 = 1.9584E-02, A5 = 0.000E + 00,
A6 = 4.6492E-03, A7 = 0.000E + 00, A8 = -2.9692E-03, A9 = 0.000E + 00,
A10 = 3.5368E-04, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
8th page
K = -0.539, A3 = 0.000E + 00, A4 = 9.9053E-03, A5 = 0.000E + 00,
A6 = -3.0707E-03, A7 = 0.000E + 00, A8 = 4.7195E-04, A9 = 0.000E + 00,
A10 = -2.9000E-05, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
12th page
K = 1.498, A3 = 0.000E + 00, A4 = 4.3758E-03, A5 = 0.000E + 00,
A6 = 9.7522E-04, A7 = 0.000E + 00, A8 = -4.1374E-02, A9 = 0.000E + 00,
A10 = 2.2549E-01, A11 = 0.000E + 00, A12 = -2.0701E-01, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 13
K = 2.791, A3 = 0.000E + 00, A4 = -6.0222E-02, A5 = 0.000E + 00,
A6 = -2.9255E-02, A7 = 0.000E + 00, A8 = 3.1562E-02, A9 = 0.000E + 00,
A10 = 1.9103E-02, A11 = 0.000E + 00, A12 = -2.9059E-02, A13 = 0.000E + 00,
A14 = 0.000E + 00
Page 14
K = 1.683, A3 = 0.000E + 00, A4 = -5.4617E-02, A5 = 0.000E + 00,
A6 = 1.8029E-02, A7 = 0.000E + 00, A8 = 7.4985E-03, A9 = 0.000E + 00,
A10 = -4.8023E-04, A11 = 0.000E + 00, A12 = 2.8887E-03, A13 = 0.000E + 00,
A14 = -1.6477E-03
Page 15
K = 15.635, A3 = 0.000E + 00, A4 = -8.9233E-02, A5 = 0.000E + 00,
A6 = 6.0443E-02, A7 = 0.000E + 00, A8 = 1.9434E-02, A9 = 0.004E + 00,
A10 = -2.1967E-03, A11 = 0.000E + 00, A12 = -3.3749E-03, A13 = 0.000E + 00,
A14 = 3.0565E-03
16th page
K = 0.000, A3 = 0.000E + 00, A4 = 2.1320E-02, A5 = 0.000E + 00,
A6 = -1.5740E-02, A7 = 0.000E + 00, A8 = 2.0593E-02, A9 = 0.000E + 00,
A10 = -5.4016E-03, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00
17th page
K = 0.000, A3 = 0.000E + 00, A4 = 3.2945E-01, A5 = 0.000E + 00,
A6 = -1.5333E-01, A7 = 0.000E + 00, A8 = 4.4352E-02, A9 = 0.000E + 00,
A10 = -4.0477E-03, A11 = 0.000E + 00, A12 = 0.000E + 00, A13 = 0.000E + 00,
A14 = 0.000E + 00

The focal lengths of each lens of Example 10 are shown in Table 30 below.
[Table 30]
Lens focal length (mm)
L1 -5.9055
L2 -2.9875
L3 6.1637
L4 8.9299
L5 2.2295
L6 -1.9049
L7 3.5876
L8 4.0013

FIG. 11A is a cross-sectional view of the imaging optical system 10J and the like according to the tenth embodiment. The imaging optical system 10J includes a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive power, a third lens L3 having a positive refractive power, and a positive lens group Gr1 as the first lens group Gr1. It is provided with a fourth lens L4 having a refractive power of. Further, the imaging optical system 10J includes a fifth lens L5 having a positive refractive power, a sixth lens L6 having a negative refractive power, and a seventh lens L7 having a positive refractive power as the second lens group Gr2. The eighth lens L8 having a positive refractive power is provided. The first and fifth lenses L1 and L5 are made of glass. The second, third, fourth, sixth, seventh, and eighth lenses L2, L3, L4, L6, L7, and L8 are made of plastic. An aperture diaphragm ST is arranged between the fourth lens L4 and the fifth lens L5. A filter F having an appropriate thickness is arranged between the eighth lens L8 and the image sensor 51.

11B and 11C show aberration diagrams (spherical aberration and astigmatism) of the imaging optical system 10J of Example 10.

Table 31 below summarizes the values of Examples 1 to 10 corresponding to the conditional expressions (1) to (14) for reference.
[Table 31]

In the above, in the actual lens measurement scene, the radius of curvature of the lens surface referred to in the present application is a shape measurement value in the vicinity of the center of the lens (specifically, the central region within 10% of the outer diameter of the lens). Refers to the approximate radius of curvature when the lens is fitted by the minimum self-squared method. Further, for example, when a quadratic aspherical coefficient is used, the radius of curvature in consideration of the quadratic aspherical coefficient is included in the reference curvature radius of the aspherical surface definition formula.

Although the image pickup optical system and the like have been described above according to the embodiment, the image pickup optical system according to the present invention is not limited to the above embodiment or the embodiment and can be variously modified.

Further, in the above embodiment, the filter F may be configured to be switched at the time of imaging with visible light or near-infrared light in applications such as in-vehicle cameras and surveillance cameras.

Further, in the above embodiment, the lens is fixed to the lens barrel 41, but it can be moved as appropriate for focusing or the like.

Claims (20)

An imaging optical system including a first lens group, an aperture, and a second lens group in order from the object side.
The first lens group has a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a positive refractive power in order from the object side. Substantially from the 4th lens that has
Of the four lenses in the first lens group, three lenses are made of plastic.
The second lens group includes at least one lens made of plastic and having a positive refractive power and one lens made of plastic and having a negative refractive power.
The side surface of the object of the second lens has a shape that is concave on the object side in the vicinity of the optical axis, but is located on the image side from the surface apex position on the optical axis at the effective diameter position.
An imaging optical system that satisfies the following conditional expression.
−0.32 ≦ F × Σ (1 / fplk) ≦ 0.32… (1)
However,
F: Focal length of the whole system fplk: Focal length of the kth plastic lens from the object side An imaging optical system including a first lens group, an aperture, and a second lens group in order from the object side.
The first lens group has a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a positive refractive power in order from the object side. Substantially from the 4th lens that has
Of the four lenses in the first lens group, three lenses are made of plastic.
The second lens group includes at least one lens made of plastic and having a positive refractive power and one lens made of plastic and having a negative refractive power.
The lens on the most object side of the second lens group is composed of a glass lens having a positive refractive power .
The glass lens located closest to the object in the second lens group is an imaging optical system that satisfies the following conditional expression.
nd5 ≧ 1.7… (10)
νd5 ≧ 40… (11)
However,
nd5: Refractive index of the glass lens on the most object side of the second lens group
νd5: Abbe number of the glass lens on the most object side of the second lens group The imaging optical system according to any one of claims 1 and 2, wherein the two positive lenses and the two negative lenses in the first lens group satisfy the following conditional expressions, respectively.
−0.47 ≦ f1n / f1p ≦ 0.00… (2)
However,
f1n: Combined focal length between the first lens and the second lens f1p: Combined focal length between the third lens and the fourth lens The imaging optical system according to any one of claims 1 to 3, wherein the three plastic lenses in the first lens group satisfy the following conditional expressions, respectively.
−0.85 ≦ F1 × Σ (1 / f1plk) ≦ 0.85… (3)
However,
F1: Composite focal length of the first lens group f1plk: Focal length of the kth plastic lens from the object side in the first lens group The imaging optical system according to any one of claims 1 to 4, wherein two or more plastic lenses in the second lens group satisfy the following conditional expressions, respectively.
−0.85 ≦ F2 × Σ (1 / f2plk) ≦ 0.85… (4)
However,
F2: Composite focal length of the second lens group f2plk: Focal length of the kth plastic lens from the object side in the second lens group The imaging optical system according to any one of claims 1 to 5, wherein the third lens satisfies the following conditional expression.
5.0 ≦ f3 / F ≦ 14.5… (5)
However,
f3: Focal length of the third lens F: Focal length of the whole system The imaging optical system according to any one of claims 1 to 6, wherein the fourth lens satisfies the following conditional expression.
7.0 ≤ f4 / F ≤ 15.1 ... (6)
However,
f4: Focal length of the fourth lens F: Focal length of the whole system The imaging optical system according to any one of claims 1 to 7, which satisfies the following conditional expression.
0.3 ≤ F1 / F2 ≤ 5.3 ... (7)
However,
F1: Synthetic focal length of the first lens group F2: Synthetic focal length of the second lens group The imaging optical system according to any one of claims 1 to 8, wherein the first lens is a glass lens. The imaging optical system according to claim 9, wherein the first lens satisfies the following conditional expression.
nd1 ≧ 1.7… (8)
νd1 ≧ 40… (9)
However,
nd1: Refractive index of the first lens ν d1: Abbe number of the first lens The imaging optical system according to claim 1 , wherein the lens located closest to the object in the second lens group is a glass lens having a positive refractive power. The imaging optical system according to claim 11 , wherein the glass lens located closest to the object in the second lens group satisfies the following conditional expression.
nd5 ≧ 1.7… (10)
νd5 ≧ 40… (11)
However,
nd5: Refractive index of the glass lens on the most object side of the second lens group νd5: Abbe number of the glass lens on the most object side of the second lens group The imaging optical system according to any one of claims 1 to 12, wherein the lens closest to the object in the second lens group satisfies the following conditional expression.
2.0 ≤ f5 / F ≤ 4.5 ... (12)
However,
f5: Focal length of the lens located closest to the object in the second lens group F: Focal length of the entire system The imaging optical system according to any one of claims 1 to 13, wherein the second lens group comprises only a positive lens, a negative lens, and a positive lens in order from the object side. The imaging optical system according to any one of claims 1 to 14, which satisfies the following conditional expression.
0.0 <Fb / L ≦ 0.2… (13)
However,
Fb: Distance on the optical axis from the image side surface of the final lens to the image formation position L: Distance on the optical axis from the object side surface of the first lens to the image formation position The imaging optical system according to claim 2 , wherein the object side surface of the second lens has a shape that is concave on the object side in the vicinity of the optical axis but is located on the image side from the surface apex position on the optical axis at the effective diameter position. .. The imaging optical system according to any one of claims 1 to 16, which satisfies the following conditional expression.
−0.32 ≦ F × Σ (1 / fplk) ≦ −0.10… (14)
However,
F: Focal length of the whole system fplk: Focal length of the kth plastic lens from the object side The imaging optical system according to any one of claims 1 to 17.
A lens barrel that holds the imaging optical system and
Lens unit equipped with. The imaging optical system according to any one of claims 1 to 17.
An image sensor that detects an image obtained from the image pickup optical system,
An imaging device comprising. The imaging device according to claim 19, further comprising a lens barrel that holds the imaging optical system.

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